Hand-held lawn trimmers such as flexible line trimmers have become very popular and widely used by homeowners to cut soft ground vegetation in areas that are inaccessible with conventional lawn mowers. The cutting element is most often a length of flexible line that is spun rapidly by a "line head" and flails the vegetation. Flexible line is comparatively safe, tends not to cause damage to structures and trees and, if the line becomes damaged, is inexpensively and easily replaced. For tougher vegetation, a rigid blade is sometimes used in place of the line head.
A typical lawn trimmer is formed from an elongated tube, a rotating cutting element mounted on a lower end of the tube and a handle attached to an upper end of the tube for enabling an operator, while standing, to position the cutting element adjacent and parallel to the ground. An auxiliary handle for the operator's other hand can be attached lower on the tube, between the main handle and the cutting element to enhance control.
In an electrically-powered trimmer, the cutting dement is mounted directly to a shaft of an electric motor mounted within a protective housing that is clamped around the lower end of the tube. Power is delivered to the motor by a 120 volt alternating current or by direct current from a battery. The battery is preferably mounted on the upper end of the elongated tube, opposite the motor, for better balance. With either power source, electrical wiring for supplying power generally runs through the elongated tube, between the electric motor in the housing and a trigger switch on the handle. An operator controls delivery of power to the motor with the trigger switch. For safety, electric trimmers must be "prewired" during manufacture by attaching the wires to both the switch in the handle and the electric motor and running the wires through the tube before packaging and shipment.
Having the wire running through the tube gives rise to several problems. Consumers frequently use lawn trimmers to cut an edge along the side of lawn. Because the handles are configured for holding the cutting element parallel to the ground, the operator must turn the trimmer over and hold it in an unwieldy manner so that the cutting element is perpendicular to the ground. To facilitate use of a trimmer as an edger, the housing of some trimmers is attached to the tube in a manner that permits it to be rotated about the tube. These trimmers are sometimes provided with a button on the exterior of the housing that operates a lock for preventing rotation of the housing on the tube. Depressing the button releases the lock and permits the housing to be rotated. However, continued rotation of the housing in one direction will twist the wire, straining the electrical connections with the motor or the trigger switch.
Electric flexible line trimmers are sometimes packaged and shipped in a "knocked down" or partially disassembled state. Traditionally, to knock down the trimmer the tube that supports the handles is manufactured in two or more sections that are separated and folded over when placed in a box. In other cases the tube may be manufactured as a single piece but not attached to the motor housing, the main handle or both to save space. An extra length of electrical wire is sometimes necessary to allow the tube pieces to be pulled apart and folded over and to prevent the end of each piece from rubbing against the wire during shipment. The trimmer may be damaged as a result of a consumer assembling the handle portions in a rough manner or forcing the extra wire into one or both tube halves.
Furthermore, although of considerable benefit in terms of cost of shipping and storage to those who sell trimmers, consumers find assembling a knocked down line trimmer to be a nuisance and an inconvenience. The electrical wires make assembly more frustrating. The end of one tube section, having a smaller diameter, slides into the larger diameter end of the other tube length and bolts inserted at the joint to secure the two sections. Proper orientation of the upper length of tube length with the lower length is frequently overlooked by first time buyers and is not discovered until after bolts are installed to secure the tube lengths, thus causing frustration and discontent. Furthermore, the consumer is faced with the tedious task of forcing the extra length of wire, which is relatively stiff, into one or both tube sections when attempting to bring them together.